Distribution unit for three-wire systems



Dec. 30, 1952 R. P. BALLOU DISTRIBUTION UNIT FOR THREE-WIRE SYSTEMS 4 Sheets-Sheet 1 Filed April 7, 1950 INVENTOR;

Hid/Yard P. .BQ'ZZOZL BY datum mu-2' Men-L Dec. 30, 1952 R. P. BALLOU 2,623,930

DISTRIBUTION UNIT FOR THREE-WIRE SYSTEMS Filed April 7, 1950 4 She ets-Sheet 2 INVENTOR. Bic/yard P .BaZZou BY Y E .F

Dec. 30, 1952 R. P. BAIILOU 3,930

DISTRIBUTION UNIT FOR THREE-WIRE SYSTEMS Filed April 7, 1950 4 Sheets-Sheet 4 if M 2/0 A92 2/0 /64 /60 A 5 Q M i g 4 266 m4 ?0 i 4% 492 w I l w l 2/0 w 204 2 L220 .m4

IN VEN TOR. fPz'c/zard F? 542201;.

Patented Dec. 30, 1952 DISTRIBUTION UNIT FOR THREE-WIRE SYSTEMS Richard P. Ballou, Hartford, Conn., assignor to Federal Electric Products Company, Newark,

N. J a corporation Application April 7, 1950, Serial No. 154,559

Claims. (Cl. 175-298) This invention relates to fuse blocks, and more especially to fused switch blocks, for three-wire distribution systems.

In the usual fuse blocks or fused switch blocks for a three-wire distribution system, it has heretofore been the practice to provide a neutral terminal block or connector device structurally separate from the fuse block itself. This is undesirable because it complicates and renders difficult the correct wiring of the several branch circuits to the companion fuse and neutral terminals, respectively, and increases the possibility of erroneously wiring the branch circuits to the companion fuse terminals.

It is, therefore, one of the objects of the present invention to provide, especially for three-wire distribution, a fuse block for a plurality of branch circuit connections each of which is provided with a companion fuse receptacle having its terminals so arranged in relation thereto on the block that they are readily apparent as being the companion live and neutral-wire terminals of the companion fuse receptacle, thereby obviating the need for a separate neutral-wire terminal block, or connector, and decreasing the possibility of errors in wiring.

Another object of the invention is to provide a compact integral distribution unit for main and branch circuit switches and fuses or circuit interrupters.

It is another object of the present invention to provide a fuse block of this type having lead-in terminals arranged to facilitate their connection with the line wires, respectively, including the neutral wire thereof.

It is another object of the present invention to provide a fused switch block of this type in which the lead-in terminals for the line wires are arranged at one end of the block near a centrally located main switch or circuit interrupter thereon, and the companion terminals for the branch circuit connections are arranged in equal rows on the opposite sides, respectively, of the block and properly connected with the disconnect side of the main switch and with the lead-in terminal for the neutral line wire by different bus bars in the block.

It is another object of the present invention to provide a fused switch block of this type having a main pull-out type switch for opening and closing all branch circuits, as well as one or more auxiliary pull-out type switches for opening and closing one or more of these branch circuits independently of the other branch circuits.

The above and other objects, features and advantages of the present invention will be more fully understood from the following description considered in connection with the accompanying illustrative drawings.

In the drawings:

Fig. l is a front elevational view of an enclosed fuse block embodying the present invention;

Fig. 2 is a side elevational view of the panel box in which the instant fuse block is enclosed;

Fig. 3 is a front elevational view of the enclosed fuse block with the cover of the panel box removed;

Fig. 4. is a section taken substantially on the line 44 of Fig-3;

Fig. 5 is a front view of the fuse block itself, drawn to a larger scale than in Figs. 1 and 3;

Fig. 6 is an end elevation of the fuse block as viewed in the direction of the arrow 6 in Fig. 5;

Fig. 7 is a rear view of the fuse block;

Figs. 8 and 9 are longitudinal sections through the fuse block taken substantially on the lines 88 and 99, respectively, of Fig. 5;

Fig. 10 is a transverse section through the fuse block taken on the line |0l 0 of Fig. 5;

Fig. 11 is another transverse section through the fuse block taken on the line I l of Fig. 7;

Figs. l2, l3 and 14 are rear, side and end views, respectively, of a main switch used in the instant fuse block; and

Figs. 15, 16 and 1'7 are rear, end and side views, respectively, of an auxiliary switch used in the instant fuse block.

Referring to the drawings, and more especially to Figs. 1 to 4 thereof, the reference numeral 29 designates a fuse block or receptacle which, in the present instance, is of the pull-out switch type and enclosed in a panel box or metal enclosure 22. The panel box 22, which is open at the front thereof, is normally closed thereat by a trim or cover plate 28 which is removably mounted on the panel box 22 in any suitable manner, as by screws 30 which are threadedly received by lugs 32, respectively, in the interior of the panel box. The fuse block or receptacle 2!] is mounted on the rear wall 36 of the panel box 22 in a manner to be described, and the trim plate 28 is provided with an inwardly offset opening 38 in which to xpose the front face 40 of the mounted fuse block 20 in the manner shown in Figs. 1 and 5. The opening 38 in the trim plate 28 is normally closed by a hinged door 42 on the latter. A latch 46, preferably of spring type, on the door 42 serves for releasably looking the latter in its closed position to a lug 48' on the trim member 28. The rear wall 36 of Referring now to Figs. 5 to 11, inclusive, there is shown the fuse block 20 which may advantageously be molded in one piece from any suitable insulating material, such as Bakelite, for instance. The block 26 is in the rear and at the top thereof provided with opposite ribs 2| (Figs. 7 and 8) by means of which the block 29 is suspended from hooks 23 on the rear wall 36 of the panel box 22 (Fig. 4). The block 20 is further secured to the rear wall 36 of the panel box 22 by screws 25 (Figs. 3 and 4). Provided in the fuse block 2d on. opposite sides of its longitudinal center line are receptacles Edand 62, respectively, for the reception of main switches 64' and 6 respectively, which, in the present instance, are of the pull-out type (Figs. 3 and 12). Provided in the receptacle E8 is a live. contact IE! which may be of the clip-type shown in Fig. 10. Contact I9 is, by means of screws 80', secured to the bottom It of the receptacle 6B and connected with a terminal 18 (Figs. 5 and 10). The terminal It, being a leadin terminal for one of the live wires of a threewire supply system, extends through an opening 82' in the adjacent end wall 84 of the block 2t (Fig. 6) and carries conventional clamp-on provisions 8B for the line wire.

Provided in the other receptacle 62 is another live contact 90. which may be of the same cliptype as the contact EU in the receptacle 5D, and is secured to the bottom SI of the receptacle 6'2 and connected with a terminal 92 by screws 94 (Fig. 10). The terminal 92, which is a. leadin terminalf'or the other live wire of the threewire supply system, extends through an opening 96. in. the adjacent end wall 84 of the fuse block 2i! and carries wire clamp-on provisions 98.

Further provided in the receptacle 6i! is another clip-type contact IDS] which is a companion to the adjacent contact I and connected with. the latter by the main switch 64 when the same. is in its circuit-closing position in the receptacle 6!) (Figs. 1 and 3). The contact Illii' issecured to the bottom I6 of the receptacle Bil and connected with a bus bar I02 by screws I04 (Figs. and 9).

Further provided in the receptacle 62 is another clip-type contact II!) which is a companion to the adjacent contact 90 and will. be connect'ed with the latter by the main switch 66 when the same is in its circuit-closing position in the receptacle 62 (Figs. 1 and 3). The contact' III] is secured to the bottom of the receptacle 6-2 and connected with a bus bar I I2 byscrews II4 (Fig; 5).

Provided on one side of the block 28 are a number of pairs of companion terminals I29 and I22, respectively, for connection with a like numberof branch circuits, respectively. Th terminals I22 are live-wire terminals, being connected with the contact [00 in the receptacle 60 in a manner hereinafter described, while the terminals I22 are neutral-wire terminals being connected in a manner to be described with a lead-in terminal I24 for the neutral wire of. the three wire supply system. More particularly,

the terminals I 20 and I22 are so closely coordinated (Figs. 4 and 5) that the terminal pairs 1213a, I 22a to I2Ile, I22e are readily recognized as the correct connections for the respective branch circuits.

The fuse block 25) is provided on the other side thereof with pairs of terminals I24 and I25, respectively, preferably for connection with the same number of branch circuits as on the oppo'site side of the fuse block. The terminals I24 and I25 are live and neutral-wire terminals, respectively, which in a manner described hereinafter are connected with the contact III) and with the neutral-wire lead-in terminal I25, respectively. As in the case of the terminals I21) and 122, the terminals I25 and I26 are arranged in closely coordinated pairs I24a, IZfia to I24e, IZfie (Fig. 5) which are readily recognized as the correct connections for the respective branch circuits.

The. connection betweenv the. contact III) and each of the live-wire terminals I24-has an interposed fuse F which may be of the screw type shown in Fig. 5. To this end, the fuse block 20 is in its front face. and along one side provided with openings I36 for the. reception of metallic sockets I32 (Fig. 8') which are associatedwith the adjacent terminal pairs I2'4a, I260. to I24e, I2 he in the manner shown in Fig. 5. Thesockets I32 serve for the reception of the fuses F. The live-wire terminals I24 are, in the present in-' stance, formed by lateral. extensions I34 on the bottoms of the sockets I32, respectively. Each terminal I24 i provided with a. screw I35 for the connection therewith of the live wire of the respective branch circuit. While each socket I32 constitutes one. terminal for the inserted fuse F, the other terminal therefor is formed by the head of a conductive screw I38 (Fig. 8) which passes through an insulating washer l t!) in the bottom of the socket and through awall H54 in the block 251, and is threadedly received by a bus bar I45 which, as shown in Fig. '7, is connected at. I43 with a conductive bar I59 that is, in turn, connected at I52 with the bus bar H2. The bus bar I58 and the sockets I32 are-held in place in. the block 26 by the screws I38 (Fig. 8). The neutral-wire terminals I25 are provided with screws which are received in a bus bar I60 that extends :over longitudinally spaced side lugs I62 on the block 2! and is secured to the endmost of. these lugs I62 by screws I64 (Fig. 7) The bus bar I63 is through a transverse bar H36 connected with the lead-in terminal I24 for the neutral line wire (Fig. '7). The transverse bar I66 extends beneath the receptacles 60 and 62 and is thus effectively insulated from the hot terminals I3 and 92 in these receptacles by the bottom 76 of the latter (Fig. 10).

The block 2!) is in its front face 4t provided with further openings I30" (Figs. 5 and 10) which, in the present instance, are equalin number to the openings I30, and adapted for the reception of sockets I32 for screw-type fuses F for further branch circuits. The bottoms of the sockets I32 have lateral extensions I34 (Fig. 10) which form the live-wire terminals I29, respectively. While each of the sockets I32 constitutes a terminal for an inserted fuse F, the other terminal therefor is formed by the head of a conductive screw I38 (Fig. 10) which passes through an insulated washer I40 in the bottom of the socket and through a block wall I 42', and is'threadedly received by a bus bar I46 which, as shown in Fig. 7, is connected at I10 with a conductive strip I12 that is, in turn, connected at I14 with the bus bar I02. The neutral-wire terminals I22 are provided with screws which are threadedly received by a bus bar I60 that extends over spaced side lugs I02 on the block 20 and is secured to the endmost of these lugs by screws I64 (Fig. 7). The bus bar I60 is connected at I65 with the transverse bar I86 which, as previously described, is connected with the lead-in terminal I24 for the neutral line wire.

Referring now to Figs. 12 to 14, the main switches 64 and 66, which in their circuit-closing position in the block 20 (Figs. 1, 3 and 4) are adapted to connect the contacts 10 and I and the contacts 90 and H0, respectively, are in the present instance identical. Thus, each main switch comprises a preferably molded insulating frame I80 having a front cover plate I82 and a depending circumferential skirt I84 which fits into either of the receptacles 60 or 52 in the block 20. Suitably mounted, as by screws I92 and I94, on the inside of the top cover plate I82 of each switch are contacts I96 and I98. Connection between the contacts I96 and I98 on each switch is made by a cartridge-type fuse 204, the contact ends 206 and 208 of which are releasably held in conductive clips 2I0 and 2I2, respectively, which are connected at 2I4 and 2I6 with the contacts I90 and I98, respectively, in each switch. The switches 64 and 66 are, in the present instance, joined by a plate 2I0 across their front cover plates I82 so that these switches form a unit for simultaneously opening or closing all branch circuits with which the instant block 20 is connected. The connecting plate 2!!! has preferably pivotally mounted thereon a handle I88 for the simultaneous manipulation of both switches 64 and 06. Instead of joining the separate switches 64 and 56 by a connecting plate 2I0, the frames I80 of these breakers may be molded as a single piece. The contacts I95 and I98 of the switches 64 and 66 will, on in sertio-n of the latter in circuit-closing position in the receptacles 60 and 62, respectively, enter between and engage the contacts 10, I00 in receptacle 90 and the contacts 90, H9 in receptacle 62, respectively, and thereby close all branch circuits. To open these branch circuits,

the switches 64 and 65 are withdrawn from the r receptacles 69 and 62 and may in inverted #pGSltion be inserted in these receptacles while the branch circuits remain open. The front face 40 of the block 20 preferably bears adjacent the receptacles 60 and E2 the legends on and off, of which the legend on is exposed and readily discernible in a side notch 220 in the top cover plate I82 of the breaker 69 when both switches are in circuit-closing position in the block 20 (Figs. 1 and 3). Conversely, if the switches 64 and 66 are inserted in the receptacles 62 and 60, respectively, in circuit-opening position therein, the notch 220 in the switch 66 will expose for ready discernibility the legend off on the block 20. Thus, an observer may at .a glance determine whether the inserted switches 54 and 6B are in circuit-closing position or in circuitopening position. In order releasably to hold the switches at and 66 in their circuit-opening position in the block 20, there is provided in one of the receptacles therein, in the present instance the receptacle 60, a spring clip 226 (see also Fig. which is insulatingly mounted and adapted to clamp the contact I98 (Fig. 12) in 6 the circuit-opening position of the switches in the block.

To protect a person, on removal of the switches 64 and 86 from the block 28 in the panel box 22, from possible contact with the only live conductors in the block, these being the live-wire terminals 18 and 92 and the live contacts 10 and 90 (Fig. 5), these live conductors 10, 18, 90 and 92 are preferably shielded by insulating covers 230 of which one is provided for each receptacle 60 and 62, although only one cover 230 is shown in the drawings. For mounting the covers 230, there are provided in each of the receptacles 60 and 62 raised lugs 232 and 234 on which may rest a cover 230 with one end 235 thereof projecting underneath the top edge 236 of the opening 96 in the end wall 84 of the block 20 (Fig. 6), while the other end of the cover may be secured, as by a screw 238, to the lug 232. Each cover 230 has a raised rib 242 (Figs. 5 and 10) which, together with the adjacent wall of the receptacle in which the cover is located, forms a guard through which the correct switch contact, but not the finger of a human hand, may move into engagement with the shielded live contact in the receptacle. Since both covers 230 are preferably alike for economys sake in their manufacture, each cover 230 is provided with another raised rib 250 to provide a shielded passage to the switchholding clip 228 in the receptacle 60.

In order to permit the connection with the instant block 20 of more branch circuits than is afforded by the terminals I20, i22, I24 and I26, there are provided on the associated live and neutral bus bars I45 and I50 further terminals 259 and 258, respectively (Figs. 5 and 6). Likewise, the associated live and neutral bus bars I46 and I00 at the other side of the block 20 are preferably provided with further terminals 250 and 232, respectively. Thus, in the present example, the block 20 described so far has provisions for connecting therewith twelve branch circuits, six on each side of the block. These branch circuits, being connected with neutral wire of the line, as described, carry current of approximately one-half the voltage of that across the live wires of the supply line, as will be readily understood.

The instant block 20 has also provisions for connecting therewith a branch circuit or circuits requiring the full voltage across the live wires of the three-wire supply system. To this end, the contacts I00 and H0 in the block receptacles and 02, respectively, are connected with terminals 210 and 212, respectively, on one side of the block 20, by way of a fused switch 214 (Figs. 1, 3 and 15 to 17). The switch 214, which is of the pullout type, is in its circuit-closing position received in a receptacle 213 provided in the block 20. The bottom of the receptacle 216 is provided with a plurality of slots 219, in the present instance 8, in four of which are exposed fixed contacts 280, 282, 284 and 206. The contact 280 is formed by a slotted portion of a metallic strip 290 (Figs. 7 and 11) which is mounted in place by having one end thereof inserted in a slotted lug 292 on the bottom wall 211 of the receptacle 216 (Fig. ll), and having its other end connected at 294 with a conductive strip 296 which is, in turn, connected with the bus bar I02 as at I14 (Fig. '1). Contact 292 is formed by a slotted portion of a metallic strip 300 (Fig. '1) which is mounted in place by having one end received in a slotted lug 302 on the bottom 211 of the receptacle 216, and by having its other end connected at 304 with a conductive strip 386 which is, in turn, connected at I52 with the bus bar H2. 'Thus, the contacts 289 and 282, being connected with the contacts we and H6 in the receptacles 6d and 62, respectively, as described, are live contacts when the main switches 64, 66 are in their circuit-closing position in the block 2% Th contacts 2% and 288, which are companions to the contacts 28d and 2&2, respectively, are formed by slotted portions of metallic strips 3H! and M2, respectively, which are mounted in place by having their inner ends 3 inserted in slotted lugs 3M and M6, respectively, on the bottom wall 2?! of the receptacle 216 (Figs. 7 and 11), and by being secured by screws M8 to one of the adjacent side lugs H52 on the block 23. The outer ends of the strips Sid and M2 may conveniently be formed into the terminals 279 and 272, respectively, in the manner best shown in Fig. 11..

The companion contacts 280, 28 and 282, 266 are, as already mentioned, bridged by the fused switch 214 in its circuit-closing position in the receptacle 216 (Figs. 1 and 3). To this end, the switch 214, which may have a molded frame 330 (Figs. 15 to 17) carries clip-type companion contacts 332, 334 and 335, 338 of which the contacts of both pairs are formed to provide receptacles 348 and 3 32 for the cylindrical contacts T of cartridge-type fuses FI and F2, respectively. The contacts 332, 334, 336 and 338 will, on insertion of the switch 214 into the receptacle 276 in circuit-closing position therein, engage the fixed contacts 284, 28%), 286 and 282, respectively, in the receptacle 27B and close the branch circuit leading from the terminals 210 and 212. To open this branch circuit, it is merely necessary to withdraw the switch 274 from the receptacle 276, unless the same circuit is already opened by the main switches 64, 65. The switch 214 may in inverted disposition be inserted in the receptacle 1 216 for safe-keeping therein while the associated branch circuit is open, in which case the contacts 332 to 333 will enter and be yieldingly held in the empty slots 2'18 in the bottom of the receptacle 216, as will be readily understood. In order to indicate to an observer whether the switch 2M is in its circuit-closing or circuit-opening position in the receptacle 216, the front face 42 of the block 2!! preferably bears on the opposite sides of the receptacle 216 the legends on and off, respectively. When the switch 214 is in its circuit-closing position in the receptacle 2 15, a side notch 350 in the switch front cover 362 exposes the legend. on adjacent the receptacle 276, while a marginal extension 384 on the opposite side of the switch front cover 362 covers the legend off on the opposite side of the receptacle 215. Conversely, when the switch 27d is inserted in the receptacle 216 in its circuit-opening position therein, a side notch 366 in the switch front cover 362 will expose the legend ofi, while the front cover extension 3% will cover the legend on. The switch 214 is for its manipulation provided with a pivoted handle 315. For ready guidance of the contacts 332 to 338 on the switch 275 into the aligned slots in the bottom of the receptacle 276 into either the circuit-opening or circuit-closing position of the switch, the latter is provided with opposite guide ribs 368 and 370 which are slidably received in opposite guide grooves 372 and BM in the block 2c.

The block 23 may, for its connection with another full-voltage branch circuit, be provided with further live-wire terminals 376 and 378 (Fig. 5) which are connected with the contacts I00 and i it in the receptacles (it and 62, respectively, by way of a pull-out type switch 380 (Figs. 1 and 2) and in a receptacle 382 in the block 28 (Fig. 5). The switch 38% may, with one exception to be described, be exactly like the described switch 2M, and its fuse-connected contact pairs will, in the circuit-closing position of the switch 380 in the receptacle 382, connect the contacts 384' and 385 and the contacts 388 and 390,.respectivly, in said receptacle. As shown in Figs. 7 and 11, the contacts 355 5 and 338 are formed by slotted portions of conductive strips 392 and 394, respectiveiy, which are similar to and mounted like the strips 34S and 352 on the opposite side of the block Zli. Also the outer ends of the strips 392 and 32 3 are formed into the terminals 316 and We, respectively (Fig. 11). The other fixedlcontacts 386 and 399 in the receptacle 382 are provided by slotted portions of the previously described conductive strips 2% and 3%, respec tively, (Fig. '7). Thus, on inserting the switch tee in the receptacle 382 into its circuit-closing position therein, in which the front cover 396 of the switch exposes the legend on adjacent the receptacle 382 (Figs. 1 and 3) the branch circuit leading from the terminals 376 and 318 is connected with the live wires of the three-wire suppiy system when the main switches 64, 66 are in their circuit-closing position in the block 28, as will be readily understood. The switch 380 is, for the correct guidance of its contacts into the aligned slots in the bottom of the receptacle 382 provided with opposite guide ribs (not shown) which are slidably received in opposite guide grooves are and see in the opposite sides of the receptacle. The guide ribs on the switch 380 are preferably differently dimensioned than those on switch 21 so that these breakers may not interchangeably be used in the receptacles 216 and 382, but only in the ones with which they are positively identified by suitable legends on their respective front covers, describing the type of service for which the respective branch circuits are intended, such as for a cooking range and for a water heater, for instance.

The neutral bus bars Mid and I66 on the opposite sides, respectively, of the block 2%! are provided with further terminals am and M2, respectively (Fig. 5). Thus, either one of the branch circuits leading from the terminals 210 and 212 and from the terminals 3'56 and 3'58, respectively, may, if desired, be supplied with current of approximately one-half the voltage of that across the live wires of the three-wire supply system, by simply connecting either side of the circuit with the adjacent neutral-wire terminal 418 or M2, as will be readily understood.

While I have shown and described the preferred embodiment of my invention, it will be understood that various changes may be made in the present invention without departing from the underlying idea or principles of the invention within the scope of the appended claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

l. A distribution unit for a three wire system, comprising an insulation body provided with two laterally spaced rows of receptacles for currentinterrupting devices, each of said receptacles having a wire terminal for a branch circuit, said terminals of the receptacles of each row being mounted on said body and disposed adjacent the companion receptacles, respectively, three laterally spaced bus bars mounted on said body in position between and parallel to said rows of receptacles, one of said bus bars being arranged for electrical connection to the receptacles of one of said rows and another of said bus bars being arranged for electrical connection to the receptacles of the other of said rows, and two further rows of branch circuit terminals electrically connected to the third bus bar and mounted on said body, the terminals of said last mentioned rows being positioned adjacent the terminals of the receptacles of said two rows, respectively, and insulated therefrom by said body, each of said terminals which are connected to said third bus bar being arranged on said body in paired branch-circuit relation with a terminal of the adjacent receptacle said body having at least a pair of additional branch circuit terminals aligned with each of said two further rows, respectively, one terminal of each of said pairs being arranged for electrical connection to said one bus bar and the other terminal of each of said pairs being arranged for electrical connection to said other bus bar.

2. A distribution unit as defined in claim 1, further comprising a first additional terminal in each of said two further rows and connected to said third bus bar, and a second additional terminal aligned with each row of receptacles, respectively, and connected to the bus bar to which its receptacle row is connected, said additional terminals being in paired branch-circuit relation, respectively.

3. A distribution unit as defined by claim 1, further comprising an additional terminal adjacent each pair of said additional branch circuit terminals, said additional terminal being arranged for electrical connection to said third bus bar and being adapted for alternative electrical connection with a branch circuit which is also electrically connected with one of the terminals of the adjacent pair of said additional branch circuit terminals.

4:. A distribution unit for a three wire system, comprising an insulation body provided with two laterally spaced rows of receptacles for currentinterrupting devices, each of said receptacles having a wire terminal for a branch circuit, said terminals of the receptacles of each row being mounted on said body and disposed adjacent the companion receptacles, respectively, three laterally spaced bus bars mounted on said body in position between and parallel to said rows of receptacles, one of said bus bars being arranged for electrical connection to the receptacles of one of said rows and another of said bus bars being arranged for electrical connection to the receptacles of the other of said rows, and two further rows of branch circuit terminals electrically connected to the third bus bar and mounted on said body, the terminals of said last mentioned rows being positioned adjacent the terminals of the receptacles of said two rows, respectively, and insulated therefrom by said body, each of said terminals which are connected to said third bus bar being arranged on said body in paired branch-circuit relation with a terminal of the adjacent receptacle, said body having at least a pair of additional branch circuit terminals aligned with each of said two further rows, respectively, one terminal of each of said pairs being arranged for electrical connection to said one =bus bar and the other terminal of each of said pairs being arranged for electrical connection to said other bus bar, each of said two further rows including an additional branch circuit terminal adjacent each of said pairs of additional branch circuit terminals, respectively, for optional use with the latter.

5. A distribution unit for a three wire system,

comprising an insulation body provided with two laterally spaced rows of receptacles for currentinterrupting devices, each of said receptacles having a wire terminal for a branch circuit, said terminals of the receptacles of each row being mounted on said body and disposed adjacent the companion receptacles, respectively, three laterally spaced bus bars mounted on said body in position between and parallel to said rows of receptacles, one of said bus bars being arranged for electrical connection to the receptacles of one of said rows and another of said bus bars being arranged for electrical connection to the receptacles of the other of said rows, and two further rows of branch circuit terminals electrically connected to the third bus bar and mounted on said body, the terminals of said last mentioned rows being positioned adjacent the terminals of the receptacles of said two rows, respectively, and insulated therefrom by said body, each of said terminals which are connected to said third bus bar being arranged on said body in paired branch-circuit relation with a terminal of the adjacent receptacle, each of said one and said other bus bars being provided with an additional branch terminal at an end thereof, and said third bus bar having an additional branch terminal in alignment with each of said two further rows, respectively, each of said latter additional terminals being disposed adjacent one of said first mentioned additional terminals, respectively.

6. A distribution unit for a three wire system, comprising an insulation body provided with two laterally spaced rows of receptacles for currentinterrupting devices, each of said receptacles having a wire terminal for a branch circuit, said terminals of the receptacles of each row being mounted on said body and disposed adjacent the companion receptacles, respectively, three laterally spaced bus bars mounted on said body in position between and parallel to said rows of receptacles, one of said bus bars being arranged for electrical connection to the receptacles of one of said rows and another of said bus bars being arranged for electrical connection to the receptacles of the other of said rows, and two further rows of branch circuit terminals electrically connected to the third bus bar and mounted on said body, the terminals of said last mentioned rows being positioned adjacent the terminals of the receptacles of said two rows, respectively, and insulated therefrom by said body, each of said terminals which are connected to said third bus bar being arranged on said body in paired branch-circuit relation with a terminal of the adjacent receptacle, an additional branch circuit terminal at each end of said two further rows of branch circuit terminals, a branch circuit terminal aligned with each row of receptacles, respectively, one of said last mentioned branch terminals being arranged for electrical connection to said one bus bar and the other of said last mentioned branch terminals being arranged for electrical connection to said other bus bar, each of said last mentioned branch circuit terminals being disposed on said body adjacent one of said additional branch circuit terminals in each of said two further rows, and an additional pair of branch circuit terminals on said body arranged for electrical connection to said one and said other bus bars, respectively, each of said additional pairs being aligned with one of said 1 1 further rows and being disposed adjacent the other of said additional branch circuit terminals in each of said two further rows.

7. A distribution unit for a three wire system, comprising a body of insulating material provided with spaced integral portions extending from opposite marginal edges thereof and below the front surface thereof, two laterally spaced rows of receptacles for current-interrupting devices defined in said front surface between said spaced portions and extending longitudinally of said marginal edges, each of said receptacles having a wire terminal for a branch circuit, said terminals of the receptacles of each row being mounted on said body and extending laterally of said marginal edges, respectively, and forwardly of said integral portions, respectively, three laterally spaced bus bars mounted on said body in position between and parallel to said rows of receptacles, two of said bus bars each having a branch underlying a row of said receptacles, respectively, and electrically connected thereto, and the third bus bar having two branches each of which is carried by the spaced portions along one of said marginal edges, and a further row of branch circuit terminals provided on each of said two branches in substantial longitudinal alignment with the adjacent terminals of said receptacles, respectively, each of said two bus bars having an additional branch provided with a pair of spaced branch terminals each of which is aligned with one of said further rows of branch circuit terminals.

8. A distribution unit for a three wire system, comprising a body of insulating material provided with spaced integral portions extending from opposite marginal edges thereof and below the front surface thereof, two laterally spaced rows of receptacles for current-interrupting devices defined in said front surface between said spaced portions and extending longitudinally of said marginal edges, each of said receptacles having a wire terminal for a branch circuit, said terminals of the receptacles of each row being mounted on said body and extending laterally of said marginal edges, respectively, and forwardly of said 4 integral portions, respectively, three laterally spaced bus bars mounted on said body in position between and parallel to said rows of receptacles, two of said bus bars each having a branch underlying a row of said receptacles, respectively, and electrically connected thereto, and the third bus bar having two branches each of which is carried by the spaced portions along one of said marginal edges, and a further row of branch circuit terminals provided on each of said two branches in substantial longitudinal alignment with the adjacent terminals of said receptacles, respectively, laterally adjacent switch receptacles integral with said body and disposed between said two laterally spaced rows of receptacles, said switch receptacles being provided with dead front pullout switches which complete the circuit between said two bus bars and said branches thereof, respectively, each of said two bus bars having an additional branch provided with a pair of spaced branch terminals each of which is aligned with one of said further rows of branch circuit terminals.

9. A distribution unit, as defined in claim 6, further characterized in that each of said two further rows includes an additional branch terminal adjacent each of said pairs of additional branch circuit terminals, respectively, for optional use with the latter.

10. A distribution unit, as defined in claim 8, further characterized in the provision of additional laterally adjacent switch receptacles integral with said body, said additional switch receptacles being provided with dead front pull-out switches which complete the circuit between said two bus bars and said additional branches, respectively, thereof.

RICHARD P. BALLOU.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,856,423 Olley May 3, 1932 2,074,861 Sachs Mar. 23, 1937 2,289,358 Hanny July 14, 1942 2,357,592 Landmeier Sept. 5, 1944 

